The present invention relates generally to a remotely controlled, hydraulically operated cutter apparatus and, more particularly, to such an apparatus for use within a conduit or pipe.
It is generally well known that conduits or pipes which are employed for conducting fluids, for example, sanitary sewer pipes, storm sewer pipes, water lines and gas lines, frequently require repair due to leakage. The leakage may be inwardly, from the environment into the pipe, or outwardly, from the pipe into the environment. Leakage of this type may be due to improper initial installation of the pipe, deterioration of the pipe itself due to aging or the effects of corrosive materials, cracking of the pipe or pipe joints due to environmental conditions such as earthquakes or similar natural or man made vibrations, or any other such causes. Regardless of the cause, such leakage is undesirable at best and may result in waste of the fluid, damage to the environment and the possible creation of public health hazards.
Because of ever increasing labor and machinery costs it is becoming increasingly more difficult, at least economically, to dig up and replace those pipes or portions of pipes which may be leaking. As a result, various methods have been devised for the in situ repair or rehabilitation of the existing pipes, thereby avoiding the expenses and hazards involved in digging up and replacing the pipes. One of the most successful such repair or rehabilitation processes which has been developed is called the Insituform process which is described in U.S. Pat. Nos. 4,009,063; 4,064,211; and 4,135,958 the contents of which are incorporated by reference herein.
Briefly, in the Insituform process, an elongated flexible tubular liner comprised of a felt or foam material which is impregnated with a thermal setting synthetic resin is installed within the existing pipe utilizing an inverting process as described in the aforesaid patents. Once the liner is in place within the pipe, the liner is pressurized from within, preferably utilizing a high temperature fluid, to force the liner radially outwardly to engage and conform to the interior surface of the pipe. The resin is then cured to form a relatively hard, tight fitting, rigid pipe lining which effectively seals any cracks and repairs any pipe or joint deterioration to prevent further leakage either into or out of the pipe.
When such a liner is installed within a pipe, such as a sanitary sewer main, which includes a plurality of connecting service entrances, such as smaller laterals which carry sewage from individual sources into the main pipe, all of the service entrances or laterals are effectively covered over and sealed by the liner. It therefore becomes necessary to either gain access to the junctures of the laterals with the main sewer pipe in order to cut holes through the liners or to provide a remotely controlled cutter to cut out the portion of the liner that covers over the service or lateral entrances.
The prior art cutter which has been previously employed for this purpose is described in U.S. Pat. No. 4,197,908. While the prior art cutter described in this patent is generally effective in cutting the liner as required to port or open the various service entrances or laterals to the main sewer pipe, the prior art cutter is relatively expensive to manufacture and to operate. In addition, the prior art cutter is unreliable primarily because it is basically electrically powered and controlled and the moisture laden sewer pipe environment frequently causes the prior art cutter to fail due to electrical short circuits and the like.
The present invention provides a remotely controlled cutter apparatus which is hydraulically operated and controlled to provide more economical, efficient and reliable service.